Process of making insulated wire



Sept. 10, 1935. w. J. HOMER I PROCESS OF MAKING INSULATED WIRE Filed July 5, 1933 FIG. 2

FIG.1

ARTIFICIAL SILK COTTON ARTIFICIAL SILK COTTON VINVENTOR WILLIAM J. HOMER em Sept. 10,1935

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I Old. (G. 111-53) 14, 108,aproeeeeoiinsulatinz-wireirdeecribed oilayenclrayon-wouldhavetohemremltinginanexpemivewire. Ioreoventheflnifliedwirehardbhasthemrequiredtd' thiaclueoieervice.

Oottonieadeeirableinniatingmaterflbelm cheapanddurabie. Ithaeheenmuchueethut theeadeoiwireeinnilatedwithcottcnarelm insulated wire in accordance with the invention. Reterringtol'lg.1,thewirelmay,iideaired.be

-iirstgivenacoatinacfenamell. Thiaiausually them,whichhreachediiretbytheeohent. 'l'neecttcnmincistightlywoimdmdtheartiwlththeartiflidikinitrchanlld'oouiitionle due to the action of the acetone. The result is that when the solvent evaporates the fibers of the cotton layer are tightly bound together.

Now the time of immersion in the bath is regulated so that it is just sufilcient to insure that a substantial portion of the artificial silk is reduced to the proper condition to enable it to impregnate the cotton. For switchboard wire insulated as described herein it is found that between one-half and threefourths of a minute gives good results. If the immersion is less than this, too small a portion of the silk layer is reduced to the proper consistency, while if the time is much longer, it is found that all of the artificial silk is reduced and the inner layer practically disappears, some of the silk being entirely dissolved and lost in the bath. Much depends on the thickness and texture of the outer layer, which must be penetrated by the solvent before it can act on the material beneath. A change inthe outer layer therefore must ordinarily be accompanied by a corresponding change in the time of immersion.

In a properly insulated wire the separate strands of the cotton layer will be found to be firmly bound together so that it can be unwound only with difficulty. It is entirely free from fraying or unraveling in ordinary usage. If the serving is forcibly unwound by tearing of the binding,

1 it is found that a large part of the layer of artificial silk has gone into the cotton. That which remains still has a more or less stranded texture but is thin and irregular because of the forcible separation from the cotton. It is impossible to show all this in the drawing.

The drawing is intended therefore as an aid in describing the process rather than as an illustration of the details of the finished wire.

Fig. 1 shows certain steps in the process of making an insulated wire according to this invention.

Fig. 2 shows certain steps in the process of making a somewhat different type of insulated wire, having a braided cotton covering instead of a plain serving of cotton. This insulated wire is especially designed for use as jumper wire.

Wire insulated with enamel, silk, rayon and other materials has heretofore been given an outer covering of braided cotton for protection against mechanical injury and some very good wire of this type has been produced and sold. It is found, however, that when a smooth surfaced ,inner insulation is used such as results from the use of artificial silk treated with acetone, the outer braiding has a tendency to slip along the inner layer of insulation. At points where the insulation is cut away for the purpose of making connections, the outer braid tends to slip back along the wire, leaving the inner layer of insulation exposed for some distance. This is objectional.

I have found that by a similar process to that which has been described, an excellent'quality of jumper wire can be manufactured which is not subject to the defect above pointed out.

The wire l2 may be given a coating of enamel ll according to the u=ual practice, and is then given a serving of stranded artificial silk M described in the preceding process. The wire is then run through a braider which puts on a braided covering of cotton l5.

The wire with its artificial silk and braided cotton covering is then run through a bath of acetone. It is found that owing to the greater thickness of the braided cotton covering and the greater dimculty of penetrating it, the wire has to be immersed in the bath for about twice as long as is the case when a plain serving of cotton is used. The treatment in the bath results in the artificial silk being partially reduced to a jelly-like state as described previously, in which condition it oozes out into the braided covering to some extent and thus effectually unites the two coverings. Thus slipping of the outer braided covering is entirely prevented.

Since jumper wire is required to be fiameproof, the wire is impregnated with chlorinated naphthalene in order to give the desired protection. The spools of wire are soaked in the hot melted chlorinated naphthalene contained in a heated tank. After the requisite saturation has been obtained, each spool is transferred as quickly as possible to a heated centrifugal dryer by means of which any excess of chlorinated naphthalene is gotten rid of. The resulting product is an excellent jumper wire, flame-proof, and having a tough braided cotton covering which is not subject to fraying and which adheres tightly to the inner covering of artificial silk.

While I have described the use of certain specific materials herein, the invention is capable of -:-cing practical with other materials so long as they act in the same way. I do not therefore wish to be limited to the exact details of the processes described herein but desire to include and have protected by letters patent all variations thereof which come within the scope of the appended claims.

WhatI claim is:

l. The process of insulating a conductor which consists in applying an inner layer of yarn made of some cellulose ester, in applying thereover an outer layer of different textile material, and in passing the conductor through a bath containing a liquid which is a solvent for the cellulose ester of the inner layer but not for the material of the outer layer, whereby the fibers of the outer layer are penetrated and are bound together by the action of the solvent on the cellulose ester underneath.

' 2. The process of insulating a wire which consists in applying a layer of yarn made of some cellulose ester, in applying thereover a layer of cotton or other textile material, in passing the conductor through a bath containing a penetrating liquid which is a solvent for the material of the inner layer but not for the material of the outer layer, and in regulating the rate at which the conductor moves through the bath so that a sufficient amount-of the material of the inner layer is reduced to bind together the fibers of the outer layer.

3. The process of insulating a conductor which consists in applying a layer of fibrous material which is capable of being rendered plastic by the application of a solvent, in applying a layer of different fibrous material under tension which is not acted on by such solvent, in saturating both layers with the solvent, thereby causing a portir-n of the inner layer to become plastic and intrud between the fibers of the outer layer, and in e crating the solvent.

4. The process of insulating a conductor, which consists in spirally wrapping a continuous length of cellulose material around the conductor to To form a covering, in applying over said covering an outer covering of fibrous material which is not dissolved by a particular liquid which is a solvent for the material of the inner covering. and in passing the conductor through a bath 

